Hi Hans
Am 11.10.25 um 12:02 schrieb Hans de Goede:
Hi,
A while ago I did a blogpost about not having the native GPU drivers in
the initrd: https://hansdegoede.dreamwidth.org/28291.html
With the Fedora /boot partition size increase there has been renewed
interest in this and as a result I got an interesting comment on
the blog post pointing out that there are EFI protocols to get EDID
info for the monitor (presumably for the one the GOP has lit up).
It would be useful to see if we can hook this up so that the simpledrm
device can report the physical dimensions of the screen and the boot
splash does not need to guess the DPI and thus does not need to guess
whether to do hiDPI scaling or not. The comment is here:
https://hansdegoede.dreamwidth.org/28291.html?thread=14467#cmt14467
and it points to:
https://uefi.org/sites/default/files/resources/2_-_AMD_UEFI_Plugfest_EDID_Spring2012.pdf
https://uefi.org/specs/UEFI/2.9_A/12_Protocols_Console_Support.html
Unfortunately I do not have time to work on this myself, hence this
email in the hope that someone else can pick this idea up.
There are now efidrm and vesadrm, which support specifically the
features that we get from the rsp. standards, hardware and bootloader.
For VESA and EFI the EDID can be transferred from grub via bootparams. A
patch [1] is on its way into upstream grub. The Linux kernel stores that
data in edid_info, from where it is picked up by efidrm and vesadrm. If
the EFI framebuffer comes directly from the EFI calls, we need to
implement this in the kernel, but the principle is the same. I also have
ideas for making this work on Coreboot.
For simpledrm, I'd rather strip if from the ability to use EFI/VESA
framebuffers and focus on simple-framebuffer DT nodes. These sometimes
come with DPI information. Maybe we could extend the DT to support EDID
as well.
[1] https://lists.gnu.org/archive/html/grub-devel/2025-10/msg00043.html
I have long been working on all this and it is now slowly coming together.
Best regards
Thomas
Regards,
Hans
--
--
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Frankenstrasse 146, 90461 Nuernberg, Germany
GF: Ivo Totev, Andrew Myers, Andrew McDonald, Boudien Moerman
HRB 36809 (AG Nuernberg)
